Here's a place where I can post my thoughts on new papers, provide updates on my projects, and post info that will eventually be on my website The Theropod Database - http://theropoddatabase.com/ . It will center on theropods, but may delve into other topics as well such as phylogenetics.

Thursday, September 11, 2014

Spinosaurus surprise

This is a post to discuss some implications of today's huge Spinosaurus reboot by Ibrahim et al. (2014).

What a cool and unexpected morphology. Stromer was right about the tiny pelvis all along! With Sigilmassasaurus and bone taxa G, I and J of Russell (1996) as Spinosaurus, we have so much more data now. Seems Lapparent (1960) had a lot of Spinosaurus material in his Carcharodontosaurus referred specimens (manual phalanx and pedal ungual from Alrar; manual ungual from Dijoua; pedal ungual from from In Abangarit). These would have been the first Spinosaurus specimens described after Stromer's work and the destruction of the originals in WWII.

Also interesting is that Medeiros and Schultz (2002) described two caudals from the Alcantara Formation of Brazil as Sigilmassasaurus. Now that we know these are spinosaurid, they're probably the first postcrania of Oxalaia.

Distal caudal vertebra UFMA 1.10.240 probably referrable to Oxalaia, described by Medeiros and Schultz (2002) as Sigilmassasaurus. From Medeiros and Schultz (2002).

Finally, with the differences noted by Russell between Kem Kem and Baharija 'Sigilmassasaurus', and those visible between the Kem Kem neotype and Baharija Spinosaurus B, it seems possible the aegyptiacus neotype is not conspecific with the Baharija aegyptiacus holotype. Awkward. Interestingly, Russell viewed the Kem Kem form as more derived, and this matches some aspects of Ibrahim et al.'s figure S2 comparison between Spinosaurus B and the neotype- the neotype has a narrower distal femur with more elongate condyles (A below), and flatter pedal unguals (D below). Was it more adapted to swimming than the Baharija Spinosaurus?

2 comments:

certainly interesting to think about the various spinosaurs of North Africa being separate. I had previously noticed that FSAC-KK 11888 has much thinner neural spines in lateral view compared to IPGH 1912 (observable here: http://spinoinwonderland.deviantart.com/art/Spinosaurus-aegyptiacus-skeletal-reconstructions-483433951)